Kangoo 5th gear gone

Gday Renault Gods, Got a 2007 Kangoo, started whining a bit in 5th gear on the freeway today and it started popping out of gear. But before I got home couldn't get it into 5th at all.



Now I can select 5th, but it's like neutral.



All other gears fine, no noises or anything. Any ideas what I could start investigating? Or defer to a mechanic?



Cheers